Gene regulatory networks influencing neuron-microglia interactions in fetal brain development.

项目总结/摘要 胎儿期是大脑发育的敏感和关键时期，其特征是神经发生波， 神经元迁移和神经网络的形成。在第一和第二个三个月，小胶质细胞是 大脑的主要免疫细胞，并参与大脑发育所必需的各种过程， 包括分泌神经营养因子和吞噬凋亡的神经祖细胞。胎儿小胶质细胞 功能障碍可导致异常的皮层分层，导致脑病理学风险增加。我们有 鉴定了大量参与小胶质细胞-皮层和皮层-小胶质细胞信号传导的配体-受体对 预测有助于人类胎儿小胶质细胞功能和胎儿大脑发育。我们观察到一致的 这些配体-受体对在脑类器官（CO）中的表达和诱导的多能干细胞衍生的 小胶质细胞与我们人类胎儿的数据。CO可以模拟早期人类大脑发育，但目前的模型缺乏 大脑的免疫系统我们的数据表明，诱导多能干细胞衍生的小胶质细胞共- 与COs（oMG）一起培养捕获了人胎儿小胶质细胞的显着表型特征。因此 系统分析小胶质细胞整合入CO后的神经成熟是使用这种方法的第一步。 一个模型系统来询问神经元-小胶质细胞相互作用如何建立的分子机制 早期大脑回路。该提案旨在使用CO和oMG来评估大脑环境如何发出信号， 相应的转录因子有助于胎儿小胶质细胞的行为和小胶质细胞与神经元的相互作用 在胎儿发育早期。在K99阶段完成的目标1中，我将检验以下假设： 将小胶质细胞转化为CO导致增强的神经成熟。此外，我将测试如何扰动的稳态 小胶质细胞中的脑环境信号传导导致小胶质细胞功能障碍和改变的神经元亚群。在 目标2，我将确定转录因子网络的人类和小鼠小胶质细胞的行为， 发育、稳态和炎症损伤后。目标2的目标是发现物种- 小胶质细胞对炎症反应的保守机制，用于改善治疗靶向和鼠 建模和发现潜在的人类特有的疾病风险因素。另外，我将检验 小胶质细胞发育转录因子在炎症损伤后重新连接，导致长- 小胶质细胞行为的持久变化和脑回路的中断。目标2的研究将在 独立阶段。我的长期目标是阐明神经元小胶质细胞的表观遗传机制 作为一名独立的调查员，在健康和疾病方面进行交流。我召集了一群不同的 熟练的导师，他们将确保我在神经发育和神经功能评估方面接受广泛的培训。 电路.我的训练将进一步加强了独特的科学环境的加州大学圣地亚哥分校的研究 社区，这是面向开发和使用尖端技术和分析 评估脑中细胞异质性和动态细胞-细胞相互作用的方法。

Project Summary/Abstract The prenatal period is a sensitive and critical time for brain development characterized by waves of neurogenesis, neuronal migration, and formation of neural networks. In the first and second trimester, microglia are the dominant immune cells of the brain and participate in a variety of processes essential to brain development, including secreting neurotropic factors and engulfing apoptotic neural progenitor cells. Fetal microglia dysfunction can lead to aberrant cortical lamination, resulting in an increased risk of brain pathology. We have identified numerous ligand-receptor pairs involved in microglia-to-cortex and cortex-to-microglia signaling predicted to contribute to human fetal microglia function and fetal brain development. We observe concordant expression of these ligand-receptors pairs in cerebral organoids (COs) and induced pluripotent stem cell-derived microglia with our human fetal data. COs can model early human brain development, but current models lack the immune component of the brain. Our data suggest that induced pluripotent stem cell-derived microglia co- cultured with COs (oMGs) capture significant phenotypic characteristics of human fetal microglia. Thus, a systematic analysis of neural maturation following integration of microglia into COs is the first step in using this model system to interrogate the molecular mechanisms underlying how neuron-microglia interactions establish early brain circuitry. This proposal aims to use COs and oMGs to assess how brain environment signals and corresponding transcription factors contribute to fetal microglia behavior and microglial interaction with neurons in early fetal development. In Aim 1, completed in the K99 phase, I will test the hypothesis that integration of microglia into COs results in enhanced neural maturation. Additionally, I will test how perturbation of homeostatic brain environment signaling in microglia results in microglia dysfunction and altered neuronal subpopulations. In Aim 2, I will identify transcription factor networks underlying human and mouse microglia behavior throughout development, at homeostasis and after an inflammatory insult. The goal for Aim 2 is to uncover species- conserved mechanisms in microglia responses to inflammation for improved therapeutic targeting and murine modeling and to discover potential human-specific risk factors for disease. Additionally, I will test the hypothesis that microglial developmental transcriptional factors are re-wired following an inflammatory insult, leading to long- lasting changes in microglia behavior and disruption of brain circuitry. Studies in Aim 2 will be completed in the independent phase. My long-term goal is to elucidate the epigenetic mechanisms underlying neuronal-microglia communication in health and disease as an independent investigator. I have assembled a diverse group of highly skilled mentors who will ensure that I receive extensive training in neurodevelopment and assessment of neural circuits. My training will be further enhanced by the unique scientific environment of the UCSD research community, which is geared towards the development and usage of cutting-edge technology and analytic methods to assess cellular heterogeneity and dynamic cell-cell interactions in the brain.